Rotary engine.



PA'TENTBD JAN. 20,1903.

IR. MN I G N I ME 0 Mn Ln 0 R APPLICATION PIL'ED 00T.12, 1901.

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4 1m MODEL.

PATENTED JAN. 20, 1903.-

J, L. McMILLAN. ROTARY ENGINE.

uruommn nun 00112, 1901.

5 SHEETS-SHEET 2.

J.- L. MGMILLAN. ROTARY ENGINE.

.110 MODEL.

'PATE'NTED JAN! 20, 1903.

APPLICATION FILED 00112, 1901.

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I 'II I: 1 17 4 .anw Iota PATENTED JAN. 20, 1903.

:r. L. MGMILLAN.

ROTARY ENGINE.

I APPLICATION FILED 00112, 1901.

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fizgia I N0 MOD I 1 1 IN J W o chest will, however, give-full understanding llNTTEn STATES PATENT ()FFICE.

JOHN L. MOMILLAN, OF ILION, NEW YORK.

ROTARY ENGINE.

EECIFICATION forming part of Letters Patent N 0. 718,653, dated January 20, 1903.

Application filed October 12, 1901. Serial No. 78,478. (No model.)

To ctZZ whom it may concern.-

Be it known that 1, JOHN L. MCMILLAN, a citizen of the United States, residing at Ilion, in the county of Herkimer and State of New York, have invented certain new and useful Improvements in Rotary Engines,of which the following is aspecification.

My invention pertains to fluid-pressure engines of the rotary type; and it consists in a number of novel features, combinations, and details whereby I am enabled to produce at comparatively small cost and in compact form an engine of relatively high efficiency, simple and durable in construction, and capable of being built of materially varying capacities with little or no change of patterns.

In the accompanying drawings, Figure l is an elevation looking at the fly-whcel side of the engine, the wheel being partially broken away to show the governor and parts beyond Figs. 2 and 3, side and edge elevations of members of the governor, hereinafter fully described; Fig. 4, a view showing the interior of one of the cylinders with the piston and rotary abutment, the valve-chest and valve being shown partly in section; Fig. 5, a perspective View of the piston and its packing; Fig. 6, a rear elevation of the engine, showing one cylinder and part of the steam-chest in section on the line a a of Figs. 1 and 2 and the other cylinder in fullrlines; Fig. 7, an end elevation of the engine with the fly-wheel removed and its shaft in section; Fig. 8, a section through one cylinder on the line y y of Fig. 7; Fig. 9, a vertical section on the line a; a: of Fig. 6; Fig. 10, a longitudinal section through the valve-chest and valve on line 2 z of Fig. '9.

In its preferred form the engine comprises two cylinders or piston-chambers and an in termediate steam chest or chamber, and such is the construction shown in the drawings and about to be described. It is to be understood, however, that a single cylinder may be employed, or that a series may be used alternating with steam-chests, and that by this mode of construction the capacity of the engine can be varied to any desired extent within quite wide limits. The description of one pair of cylinders with the interposed steamof the various features of the invention.

Referring again to the drawings, A indicates a steam chest or chamber of generally cylindrical form, cast or furnished with a base or bed plate, and B B two steam cylinders or chambers of the same general form or outline as the steam-chest. Each main cylinder B, as also the steam chest or chamber A, is formed with a secondary cylindrical chamber or enlargement O of smaller diameter, the circumference of which cuts that of the main cylinder or chamber, as seen in Figs. 1, 4, and 7. V

D indicates the main shaft of the engine, extending horizontally and axially through the steam chest and cylinders with the engine in the position indicated, and E indicates a similar horizontal shaft extending axially through the smaller chambers or secondary cylinders, as seen in Figs. 1, 4, 7, and 9. Both shafts are carried in suitable hearings in the cylinder-heads.

Keyed or otherwise made fast upon shaft D are gear-wheels F F, one within each main steam-cylinder B B and closely filling the same from side to side, but of materially smaller diameter than the cylinders. G G indicate similar gears keyed or otherwise made fast upon the shaft E and of dimensionsto closelyfill the secondary cylinders O 0 not only from head to head, but also throughout their full diameter. The gears F F mesh with the gears G G, as best seen in Figs. 4 and 7.

Gears F F are each providedwith a piston H in the form of an enlarged gear-tooth reaching from the body or periphery of 'the gear proper to the inner wall of the cylinder or steam-space, as shown in Fig. 4.

Each gear G is cut away or provided with a recess I to receive a piston H of the coacting gear F, the piston and recess being preferably of semicircular form to insure easy entrance, travel, and exit of the piston and to maintain as nearly as practicable a filling of the recess by the piston during their cooperation.

The gear-teeth of the gears F and G, including the piston H and recess I,which are, in effect, larger teeth, insure simultaneous and equal rotary movement of the gears and shafts if either be turned.

Gears G G are so framed in or inclosed by their chambers or cylinders that they form abutments or stops to preclude the escape of steam past them, the meshing teeth of companion gears F and G acting to prevent passage of steam between the peripheries of such gears.

Each steam-cylinder is further formed or provided with a valve-chamber J of circular cross-section, the axis of which is advisably parallel with the axes of shafts D and E. Within the valve-chambers J and extending across the intervening steam-chest is a rocking-valve K of tubular or hollow form and having three openings a, b, and 0 through its periphery. The first of these openings is in that portion of the length of the valve falling within the width or axial measurement of one steam-cylinder B, the third is opposite the second steam-cylinder, and the intermediate one is opposite the steam-chest A, as will be seen upon reference to Fig. 10. The mid-length of the valve is wholly uncovered within the steam-chest A, hence can at all times take steam through opening Z); but steam can pass from the interior of valve K to either steam-cylinder only during such time as the opening ct or c registers partially or wholly with one or another of two inletports (1, connecting valve-chamberJ with the interior of the respective steam-cylinders B, as illustrated in Fig. at. The openings a and c are set at different angular distances or points about the axis of the valve J. Hence with the openings (1 in alinement the openings a and 0 can only come into register with the ports d d at difierent times or in alternation, the ports d being midway between the openings at 0 when the valve is in its medial position or at its mid-throw.

The valve-chamber J and its ports d d are so located with reference to gears F G and piston H as to deliver steam between the piston and gear G just after the piston completely withdraws from recess I and after the teeth of the gears enter again into mesh or engagement, as illustrated in Fig. 4. By thus locating the ports steam is caused to act upon the piston at the earliest stage of a revolution thereof consistent with safety against escape of steam between the two gears and with as small a space to be filled with steam as is practicable.

The period or the portion of a revolution of the piston during which steam is admitted to the cylinder is determined by the dimensions of the ports and the throw of the valve, and the latter is in turn regulated by a fly-wheel governor of any usual or approved construction. In Figs. 1, 2, and 3 I have illustrated such a governor and shown the manner of combining it with the engine and its Valve. In said figures, L indicates the fly-wheel, secured upon shaft D, and M indicates a diamond-shaped block pivoted or fulcrumed at one end to the web of wheel L and having at or about its mid-length a slot or elongated opening c to permit the passage through it of the shaft D and the play of said block about its pivot and relatively to the shaft. N indicates a lever fulcrumed at a point between its ends to the web of wheel L, bearing at one end a weight 0 and connected at its other end by a link P to the free or swinging end of block M. The weighted end of lever N is connected by a strap or band Q and link R with one end of a leaf-spring S, of elbow form, fulcrumed on a stud T, carried by fly-wheel L. The short arm of spring S is perforated to encircle a screw U, screwed into the rim of fly-wheel L and provided with nuts f and jam-nuts g on both sides of said short arm. By adjusting the nuts the spring S can be made to exert varying degrees of strain upon lever N and through it upon the block M, tending to move it to and retain it in the position indicated in Fig. l.

Formed upon or secured to the side face of block M is a circular boss or hub V, which under all adjustments of block M is somewhat eccentric to the axis of shaft D, but the eccentricity of which varies according to the varying adjustment of the block or carrier M. It will be seen that as the fly-wheel rotates centrifugal force will be generated, tending to move the weight 0 outward and to rock the lever N upon its pivot, thereby acting through link P to move the block or carrier M to the right as the parts appear in Fig. 1, and thus to bring the center of the cam or eccentric V more nearly into coincidence with the axis of shaft D. As this eccentricity is reduced the throw of the eccentric is proportionately lessened, or, in other words, the diameter of the circle described by that point in the circumference of eccentricV most distant from the axis of shaft D is reduced. The eccentric hub or boss V is encircled by a strap WV, of usual construction, which is connected by a rod X with a crank-arm Y, secured upon one end of the tubular valve K or upon a spindle formed upon or made fast to said valve and having a common axis therewith, which stem or spindle passes through a stuffing-box in the cylinder-head, as shown in Fig. 10.

From the description thus given it will be apparent that as the speed of the fly-wheel and shaft D increases the centrifugal force generated in weight 0 will become greater, and upon the attainment of a certain speed with reference to which the parts are previously adjusted this force will overcome the resistance of spring S and will cause lever N to rock about its pivot and to swing the eccentric carrier or block M upon its fulcrum or pivot in a direction to lessen the throw of the eccentric, and consequently to reduce the range of movement or extent of rocking of valve K.

As the ports a c of valve K can fully register with the ports (Z only upon a full or extreme throw of the eccentric, it follows that if the throw be reduced in the manner explained the ports will be but partially opened and that they will be kept open through a ICC smaller portion of a revolution of shaft D than when the eccentric is adjusted for full throw. Hence the regulation of the steam-su pply will be automatic and directly proportionate to the speed of the engine. As the speed in turn depends upon the load of the engine, it is obvious that the steam-supply will at all times be proportionate to the load or work to be performed.

It is desired to use the steam expansively. Hence the ports are so located and are of such size that under thepredetermined maximum throw of the valve the supply-port of each cylinder shall begin to open when the piston H is in the position indicated in Fig. 4, reach its maximum opening on approximately an eighth of a revolution, and completely close on a further eighth-revolution, or, in other words, that it shall completely open and completely close again all in aquarter-revolution, or thereabout. While this is the preferred arrangement, I do not mean to be understood as restricting myself arbitrarily to any definite proportion or relation between the times of opening and closing of the valve and the revolution ofthe shaft; but it is merely stated as the preferred arrangement and is that indicated in the drawings.

Pistons of successive cylinders will be set at dii'i'ereut angular adjustments about the axis of shaft D, preferably one hundred and eighty degrees apart, so that the pistons of alternate cylinders,if more than two be used, shall occupy like positions, as will also the ports for such cylinders.

It is of course important to so pack the piston as to reduce to a minimum the escape of steam past it, and to this end it is provided with a packing-strip extending across its outermost face and its ends or sides and lying in a plane radial to the axis of the shaft D. This strip Z (shown in Figs. 4, 5, and 6) is composed of two similar parts, each of L shape or comprising two branches, one at a right angle to the other. The piston H is recessed at its sides or ends and along'its outermost face to receive the members of the packing-strip Z, and the sidewalls of the groove in the outer face of the piston are themselves grooved to receive guide-ribs h, formed upon the strip members Z. The recesses in the piston H to receive the strips Z are cut away obliquely at the meeting-point of the end grooves and that on the periphery of the piston, as shown in Figs. 5 and 6, and the angles of the strips Z are filled in to correspond and are provided with studs 2', which stand at angles of fortyfive degrees to the axis of shaft D, as seen in Fig. 6. These studs enter sockets in the piston H and are pressed outward by springs j, which byreason of the angular position of the studs 'i tend to press the strip members Z both against the cyli nder-heads and against the inner curved surface of the cylinder. The ribs It being held in the grooves It prevent the strips Z from moving unduly outward or escaping when the piston is moving from the recess 7; of rotary gear or abutment G to the position indicated in Fig. 4.

As shown in Figs. 5 and 6, the proximate ends of the strips Z are cut away in such manner as to overlap each other, and thus to prevent escape of steam past the packingstrip under any adjustment that the same may assume in use and after wear. The ribs it should fit the grooves is somewhat loosely, so as to allow a limited radial movement of the strips Z.

The piston H may be made integral with the gear F, if desired; but it is deemed better for convenience, simplicity, and accuracy of construction to make it separate, as indicated in Figs. 4 and 5, with a neck or tang to enter a groove or seat formed in the gear, in which'it may be held by suitable pins or keys 1. As above indicated, however, this feature of construction is a matter of option or judgment.

It will be seen that the gear G will at each revolution carry its recess I into and through the live-steam space of the cylinder 13 and that consequently said recess will become filled with live steam, which in the absence of other provision will be discharged bodily into the outlet m at full pressure. To guard against this and to utilize the expansion of the steam contained in said space or recess, together with that of the steam in the cylinder proper, I provide in one cylinder-head or in both heads of each cylinder a recess 12, Figs. 4 and 8, extending from a point slightly above the circumference of gearwheel G downwardly to a point indicated by dotted lines in Fig. 4that is, to a point Where it shall cease to communicate with the opening or recess I only when the forward wall of said opening is in close proximity to the outlet m. This represents one-half a revolution or slightly more than a half-revolution of the gear-wheel or rotary abutment G from the position indicated in Fig. 4, or, in other words, the recess I will be carried from the full-line position to and slightly beyond the dotted-line position before the recess I will cease to communicate by way of the channel or recess 'n with the interior of cylinder B on the steam-receiving side. As a consequence of this construction the steam contained in the space I will during this half-revolution of the gear-wheel or abutment G escape into and expand within the cylinder B on the pressure side of the piston H. Hence the force of its expansion will be added to the direct pressure and expansive force of the main body of steam entering the cylinder and acting upon piston H. The steam being thus permitted to flowinto and expand within the cylinder B, there will be but very slight loss incident to the filling of recess I with live steam. The relatively small quantity of steam entering the interdental spaces of the gear will be in whole or in part lost;

but this loss will be found relatively small and more than offset by the advantages otherwise gained.

Passages m communicate with a chamber 0, formed in the steam-chest or chamber-casting, but beneath and distinct from the steamchamber A proper, as shown in Fig. 9.

In casting the cylinders openings 29 are left in the cylinder-heads through which the exhaust-steam passing from cylinders B through the outlets 1% may enter the chamber 0 on its way to the outlet q. A suitable inlet-pipe r communicates with the steam chamber or chest A, preferably at its top, as indicatedin the various figures.

In an engine of this character it is very desirable to reduce as much as possible the friction of parts. To this end the shafts D and E are both carried in roller-bearings, two of those of shaft D being shown in Fig. 6 and those of both shafts being shown in Fig. 9 in cross-section. The bearings are produced by making the shafts with suitable cylindrical enlargements s and encircling such enlargements with rollers 6, arranged in groups or series preferably spaced and held at proper distances apart by hoops or rings it, through which pass the axles or gudgeons of the rollers t, as shown in Figs. 6 and 9.

The walls or heads of the cylinders and of the steam chest or chests are made with circular chambers to receive the rollers and preferably of a size to receive also hardenedsteel wearing-rings 1). Where it is necessary to make the side opening of any of these recesses larger than the collar or enlargement s to permit the introduction of the latter or the introduction of the rollers and wearing-rings, a sleeve or collar w or a), Fig. 6, is applied to the opening to prevent undue passage of steam from the cylinder into the roller-bearing. Bonnets or cap-plates y are applied to the cylinder-heads where the shaft D passes through, and these are in turn provided with stufiing-glands .2, as best seen in Fig. 6. The hearings will or may be provided with lubricating-cups or may run in oil, as is common in many classes of machinery at the present time.

As seen in Fig. 6, the cylinders and steamchest and their heads are formed with radial flanges a, which are perforated to receive tie-bolts b, which extend through the flanges of the several parts and tie all together. The abutting faces may be dressed true and brought into immediate contact with or without the application of red lead, litharge, or like substances, or very thin packing may be employed. This latter expedient will not ordinarily be resorted to, however, because it is liable to interfere with the perfect filling of the space between cylinder-heads by the pistons and gears. It will be seen that by this mode of construction the number of cylinders and steam-chests combined in a single engine may be Varied considerably without any change whatever in the patterns, either as to form or dimensions, and that with a cylinder representing a certain unit of power it is practicable to build an enginerepresenting multiples of that unit up to a given size by merely multiplying or increasing the number of cylinders and intervening steam-chests and using tie-bolts long enough to reach through and bind together the entire series. This capability is one of very considerable importance, and by providing several difierent sets of patterns, each as a unit for engines between certain capabilities or powers, it is practicable to build engines of widely-varying capacity with a very limited number of patterns and with comparatively few special machines or appliances, since in each group a single set of patterns suffices, and these patterns are few in number and simple in character.

It will be found expedient to place a thin metal shield 0 about the engine and within this a sheet of asbestos or like material to prevent escape of heat and to preclude a chilling of the cylinders by the external atmosphere. This is indicated in Fig. 6.

Some of the advantages incident to the construction set forth are compactness and simplicity coupled with high speed. Practical experience has demonstrated the advantage of a quick or prompt use of the steam. Reciprocating engines of the ordinary types and of from twenty-five-horse power upward cannot be safely or advantageously run above three hundred revolutions per minute, whereas a rotary orcontinuous straight-ahead motion permitsaspeed many times higher,so far as concerns jar or strain upon the parts. In the relatively slow use of steam condensation or chilling materially reduces the expansive effect of the steam or allows such escape of heat units as results in a less economical utilization of the steam. Hence a prominent object sought and one in great measure attained by my construction is the prompt use of the steam.

The slight loss of steam incident to the filling of the spaces between the teeth of gearwheel G and to the carrying of steam in space or recess I to the escape-port is not only materially reduced by causing the steam in the space I to act expansivelyin the steam-space ot' the cylinder and to expend nearly all its force before exhausting, but is more than compensated for by the direct or continuous movement of the parts, the freedom from loss through stopping and starting repeatedly a mass of metal, and the absence of waste incident to cushioning the piston near the end of each stroke, as is done in reciprocating engines.

It is feasible to make this engine reversible and also to compound it by leading the exhaust-steam from one cylinder into another cylinder; but these matters are notillustrated or described in detail in the present IIO application, which is directed rather to the general features of construction above set forth.

By making the rotary piston 11 and rotary abutment F with gear-teeth I avoid the necessity hitherto existing in engines of somewhat similar construction of using external gearwheels to produce synchronism of movement, and I produce a more perfect barrier to the passage of steam between the proximate faces of these parts than would otherwise be practicable. I also avoid the danger incident to exposed gearing, both of injury to the gearing and of accident to those working about the engine. At the same time I lessen the length of the engine in the direction of the axis of the main shaft, as compared with those employing external gearing.

The gears F and G are, as shown in the drawings, in the nature of drums or, in other words, are broad-faced gears, the teeth of which extend from one end wall or head of the cylinder to the other. They may and preferably will be made hollow to render them light and to economize in material; but this is optional.

While I have above indicated apreference for an arrangement of the pistons directly opposite each other, or one hundred and eighty degrees apart, this is not to be understood as applying in all cases. Where more than two cylinders are employed, it may, and often will be, advantageous to set the pistons at regular intervals about the shaft-say in the case of three cylinders one hundred and twenty degrees, in the case of four ninety degrees, and so on; but the matter is wholly optional. Whateverbetheangular positions or relations of the pistons, however, the steaminlet ports must of course be arranged with due regard thereto.

I have shown and described a governor applied to and cooperating with the engine,

whereby its action is made steady and uniform and the highest efficiency is insured. This matter, however, is not claimed in the present application, being removed therefrom in compliance with official requirement and because under Office classification it is treated asaseparateinvention. Theillustration and description are, however, retained in order that the construction and operation may be understood as actually embodied in the working machine.

Having thus described my invention, what I claim is-- 1. Theherein-described engine, comprising two steam cylinders and an intermediate chest or chamber; two intermeshing gears in each steam-cylinder, one concentric with and the other eccentric to such cylinder, the concentric gears being each provided with a piston, and the eccentric gears having each a recess to receive such piston; and a valve controlling delivery of steam to the steam-cylinders, substantially as described and shown.

2. In an engine, the combination of two steam-cylinders; an intermediate steam chest or chamber; a main shaft passing axially through said cylinders and steam-chest; pistons carried by said shaft and arranged one in each steam-cylinder; a second shaft passing through the steam cylinders and chest and carrying two rotary abutments, one in each steam-cylinder; and a valve likewise extending through the steam-chest and communicating with the steam-chest and with both cylinders, substantially as described.

3. An engine, comprising a plurality of steam-cylinders, successive cylinders being separated by a steam chest or chamber; a shaft passing axially through said parts and carrying a plurality of pistons, one in each steam-cylinder; a second shaft parallel with the first and carrying a plurality of rotary abutments, one in each steam-cylinder, adapted to coact with the pistons therein; a valve extending into alternate steam-chambers and through the intervening steam chest or chamber and in constant communication with the latter; ports in said valve and in the respective steam-cylinders, whereby communication may be established and cut off by said valve between the steam-cylinders and the steam-chest; and connections between the main shaft and the valve, whereby the latter is caused to open and close communication between the steam-chest and the steam-cylinders at proper times.

4. In combination with cylinder B having suitable heads and provided with secondary chamber or enlargement C and valve-chamber J; shaft D provided with gear F and piston H; shaft E provided with gear G having recess I; and valve K provided with a port adapted to be brought into communication with a port at of the steam-cylinder.

5. In combination with steam-chest A having inletr and exhaust-ohambero; steam-cylinder B abutting against said steam-chest and provided with inlet-port d and with exhaustport m and passage 19; valve K controlling the port d; shaft 1) concentric with the cylinder B; gear-wheel F carried by shaft D; piston H carried by the gear F; shaft Eparallel with shaft D; and gear-wheel G carried by shaft E and provided with recess I to receive the piston H. r

6. In combination with a steam-cylinder, a revolving piston arranged therein; a rotary abutment having a recess I to receive said piston; an induction-port located in proximity to the rotary abutment; a valve controlling said induction-port; and a channel or passage formed in a wall of the cylinder and extending from a point in proximity to the induction-port'to a point distant therefrom, whereby steam entering the piston-receiving recess of the rotary abutmentis permitted to pass from said recess into the main steamspace of the cylinder, and to expandtherein after the steam-induction port is closed.

7. In combination with cylinder 13, shafts D, E, gears F, G, the latter provided with recess I, and piston H; passage-way or channel 97. serving to maintain communication between the recess I and the steam-space of the cylinder during a portion of the revolution of the gear G, substantially as and for the purpose set forth.

8. In combination with the cylinder and revolving piston of an engine of the character descrihed,apackingcomprising two L-shaped sections overlapping on the peripheral face of the piston and extending radially along the end faces thereof; and springs each arranged to bear against the inner face of one or the other of said L-shaped strips at the angle thereof and to force the same obliquely outward.

9. In an engine of the character described, and in combination with the piston H thereof having grooves or recesses to receive it, a packing-strip Z, comprising two angular sections each extending across one side or end of the piston and partly across its peripheral face, the ends overlapping on said peripheral face; and two springs each arranged to press obliquely into the angle on the inner face of one or the other packing-strip and to move the same out both radially to and in the direction of the axis of revolution of the piston.

10. In an engine of the character described, the combination with a steam-cylinder, of a piston H; packing-strips Z provided with studs 2'; and springsj bearing against the studs and serving to move the strips outward obliquely to the axis about which the piston travels.

11. In combination with a cylinder and a steam-chest, each provided with a seat or chamber concentric with the cylinder; a shaft passing axially through the cylinder and the chest; and rollers interposed between said shaft and the walls of said seats or chambers and having their axles connected by spacing rings or bands, substantially as described, whereby the rollers are prevented from making frictional contact with each other and are caused to afford a rollingsupport for the shaft, substantially as described.

12. In combination with steam-chest Aand cylinder B having recesses to receive them; wearing-rings 'u; rollers t arranged to travel in contact with said rings; and shaft D supported by the rollers 25, substantially as shown and described.

13. In combination with the steam-chest A and cylinder B each provided with recesses to receive roller'bearings; rollers mounted in said recesses; a shaft carried by said rollers; and collars applied to and closing the mouths of the recesses to exclude steam therefrom, substantially as set forth.

In testimony whereof I have signed my name to this specification in the presence of two subscribing witnesses.

JOHN L. MCMILLAN.

Witnesses:

O. H. J OSLYN, HARRY FAKE. 

